1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor light-emitting device.
2. Description of the Related Art
Generally, after a plurality of light-emitting device sections are formed by laminating a semiconductor layer, made of GaN or the like, on the surface of a large-scale and thin substrate and then forming an electrode section, LED (Light-Emitting Diode) chips are manufactured by dividing the substrate for each light-emitting device section mentioned above using a scribing method.
In recent years, with the miniaturization and high performance of LED chips, an important issue has been raised regarding how many LED chips to cut out from one substrate without damaging the light-emitting device section of the LED chip in a scribing step.
A scribing method is a method in which scribing grooves are provided so as to divide the substrate for each light-emitting device section mentioned above using a laser or a blade, and then a cleaving blade is pressed along the scribing grooves, and the substrate is cleaved lengthwise and crosswise to cut it.
Patent Document 1 (Japanese Unexamined Patent Publication No. 2004-186340) discloses a method of cleaving a compound semiconductor wafer. Scribing grooves are formed so as to cross a first groove having a continuous line shape and a second groove having a dashed line shape, and cleaving is performed in the scribing grooves, so that damage, such as chipping and the like of the corners, is prevented.
Since a method of cleaving the substrate is adopted in the scribing method, the substrate can be divided, and thus chipping of the corners is reduced. However, a sapphire component commonly used as a substrate material of the LED chip is too rigid to be processed. Therefore, even when the scribing method is used, small cracks are generated, and thus chipping often occurs.
When an n-type semiconductor layer, an active layer, a p-type semiconductor layer and the like are exposed due to the occurrence of chipping or poor separation, there may be a case where leakage occurs in the LED chip. For this reason, it is preferable to divide the substrate, insofar as possible, so as not to generate chipping or poor separation.
FIG. 8 is a unit cell diagram illustrating a sapphire crystal. As shown in FIG. 8, the sapphire is a single crystal made of hexagonal aluminum oxide (Al2O3), and has crystal planes such as a c-plane (0001), a-plane (11-20), r-plane (1-102), and m-plane (1-100). In addition, the sapphire has a c-axis, a-axis, and m-axis, which are perpendicular to the crystal planes such as the c-plane (0001), a-plane (11-20), m-plane (1-100). Here, −1 means that a bar is added onto 1, and −2 means that a bar is added onto 2. The m-plane (1-100) parallel to the a-axis direction is an easily cleaved plane.
When the LED chip having a rectangular shape in plan view is formed by the scribing method using the sapphire substrate, for example, the scribing grooves are formed so that the long side of the LED chip is made to be parallel to the m-axis direction of the sapphire substrate, and the short side thereof is made to be parallel to the a-axis direction of the sapphire substrate.
When the LED chip having a rectangular shape in plan view is cut out from the sapphire substrate, first, the substrate is cleaved along the scribing groove parallel to the a-axis direction, which serves as the short side of the LED chip, and a plurality of bar-shaped substrates are formed. Next, the substrate is cleaved along the scribing groove parallel to the m-axis direction from the bar-shaped substrate, and the LED chip having a rectangular shape in plan view is manufactured.
On the short side of the LED chip, since the cleavage is performed along the plane (easily cleaved plane) parallel to the a-axis direction, a plurality of bar-shaped substrates can be formed without chipping or poor separation occurring. However, on the long side of the LED chip, since cleavage is not performed along the easily cleaved plane, there is a problem in that chipping or poor separation is generated.